Introduction
Pluto is a tiny dwarf planet lying at the Kuiper belt that has the largest volume and second …show more content…
Earth's radius is 5 times larger than Pluto's (Stern, S. A.; et al., 2015). For the mass of Pluto, it is about 0.002 of Earth's, 0.2 of the Moon (Buie et al., 2006). Surprisingly, Pluto has a ‘big' atmosphere though both its mass and gravity are small - the extended range of Pluto's atmosphere is 13 times larger than that of Earth's, which is roughly 1600 kilometres. The composition of Pluto's atmosphere is mostly nitrogen with a small amount of methane and carbon monoxide and all of them are the products of their ices' evaporation from the surface of Pluto (Stern et al., 2015). This wide-ranged atmosphere may due to the small gravitational force between the Pluto and the atmospheric atoms, i.e. it is not capable of attracting the whole atmosphere. Newton's theory of gravitation states thatF=Gm1m2r2, where G is Pluto's gravitational constant, m1 is the mass of Pluto, m2 is the mass of atmosphere and r is the distance between Pluto's core and atmosphere. Pluto's gravitational force on atmospheric atoms is moderately small. Also, it may relate to the low atmospheric surface pressure, which is 1 Pa as measured by New Horizons, about 100000 times smaller than